Sauropod Vertebra Picture of the Week

10 Responses to “Photography and illustration talk, Part 4: Scale bars”

1. Anonymous Says:

   
   February 15, 2014 at 4:29 pm

   Is there any chance that if you placed the scale bar at two different heights you would obtain different measurements for the same specimen? I am particularly thinking of small fossils (lizards and micromammals) in which it may not be feasible to directly measure the specimen by hand.
2. Mike Taylor Says:

   
   February 15, 2014 at 9:30 pm

   Absolutely! That is why we at SV-POW! have a strict MYDD policy.
3. Anonymous Says:

   
   February 15, 2014 at 9:43 pm

   How would one go about measuring small specimens though, where they are too small to feasibly measure with calipers and subject to large parallax effects under a microscope?
4. 220mya Says:

   
   February 15, 2014 at 10:39 pm

   Also, for goodness sake, people please stop publishing figures with the original scale bar in them – its messy and unprofessional. Trace over it in your favorite vector graphics program and create a nice clean digital scale bar that is well-placed and oriented perfectly horizontally or vertically.
5. Mark Robinson Says:

   
   February 16, 2014 at 3:32 am

   One way to avoid having to decide where in the camera’s depth of field to place your scale bar would be to use a scale board placed obliquely relative to the depth of field. It could be made of a transparent material and have linear markings more like a traditional ruler (but full “width” – top to bottom) so as not to obscure too much of the specimen.

   It wouldn’t be as clear as a black & white scale bar but it doesn’t need to be since you can easily tweak your digital photos using your favourite software later. Of course, you should prob always take two of each and every photo – one with a scale and a clean one without. However, if you follow Randy’s advice above, and go with only a digitally added scale bar, it’d be helpful if it was also stated where the scale bar is in relation to the specimen.

   Of course, none of this is any substitute for MYDD.
6. Mike Taylor Says:

   
   February 16, 2014 at 8:55 am

   Anonymous, photographing and measuring small specimens presents its own problems. Fortunately, they’re not ones we have to deal with here at Sauropod Vertebra Picture of the Week. For that, you probably want Small Boring Fossilised Pollen Grain of the Week.

   Randy, good point on including physical scale-bars in figures. It’s particularly annoying when a scalebar obscures the very morphology we’re interested in.

   Mark, the scaleboard idea is interesting. Do these exist, or have you just made them up?
7. Mark Robinson Says:

   
   February 17, 2014 at 2:39 am

   Mike, I’ve never seen one or even heard of them but if I thought it might be a good idea only yesterday, I’m sure someone else has thought of it long before and prob taken the next step and actually made one.

   Just asked Professor Google about scale boards but he only knew of circuit boards for electronic scales. I did find some thin (1mm!) chopping boards from China but they were translucent rather than transparent, and only had a cm scale near one edge.

   Might as well give you the link: xxx.aliexpress.com/item/Free-shipping-transparent-chopping-block-plastic-ultrathin-fruit-cutting-board-vegetable-chopping-board-with-scale-kitchenware/616050888.html (replace “xxx” with “www”).
8. Matt Wedel Says:

   
   February 17, 2014 at 2:59 am

   For specimens that aren’t flat-out immense, a clear plastic ruler might work. Although the more I think about it, the more I think having the board be transparent is nice but not essential. Just take two photos, one with no ruler or meter stick, and a second one with a ruler or meter stick angled through the shot. There’s still the problem of registering that to the specimen. If it had a couple of sliding jaws or pointers like a caliper, you could use one to indicate the “front” of the specimen (whichever bit is closest to the camera) and the other to indicate the “back”.

   BUT I am now pretty well convinced that trying to get a single scale bar to tell you very much in a single-angle photo is waste of time, for two reasons. First, MYDD, and second, photogrammetry, which is coming up in a future batch of slides. As Martin Sander put it to me, photogrammetry is now so cheap and so easy that there is just no reason not to do it. So put one big scale bar next to the specimen or several smaller ones scattered around it, or both, and you’ll be able to extract whatever measurements you want from the digital model. That’s assuming the model is distortion-free, of course, but the best way to achieve that is to focus on getting plenty of good photos from multiple angles; having the scale bar perfectly placed is probably less important than just having one, period.
9. Mark Robinson Says:

   
   February 18, 2014 at 5:35 am

   Matt, you’re prob right that we’re a few years late in worrying too much about the use of scale bars/boards/calipers. How many more years before it becomes common-place to include detailed 3-D model data so that I can produce my own copies of smaller bones on my $500/300 Euro printer and, say, universities anywhere can print off a copy of “the Archbishop” (you know, when Mike eventually finishes it ;-)?
10. Wild Proboscidea in Oklahoma | Sauropod Vertebra Picture of the Week Says:

    
    March 20, 2016 at 10:59 pm

    […] didn’t put any scale bars in these photos – I should have, despite their inherent dangers – but if you’re curious, this particular seed pod is […]

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